Method for producing bulky yarns



METHOD FOR PRODUCING BULKY YARNS Filed March 30. 1966 Shr/h/rage Temperafure (6) United States Patent 3,439 393 METHOD FOR PRODUCING BULKY YARNS Yoshiaki Mnrcno, Fuji-shi, Japan, assignor to Asahi Kasei Kogyo Kabushiki Kaisha, Osaka, Japan, a cor- I poration of Japan Filed Mar. 30, 1966, Ser. No. 538,683 Claims priority, application Japan, Apr. 1, 1965, 40/ 18,652 Int. Cl. D0411 N50 US. Cl. 28--72 7 Claims ABSTRACT OF THE DISCLOSURE A method for producing a high bulk yarn by spinning high shrinking synthetic fibers having a shrinkage of less than of its original length in hot water of from 95 C. to 105 C. and a shrinkage of from 8% to 35% of its original length with steam of from 115 C. to 140 C. with low shrinking fibers having a shrinkage of less than 10% of its original length with steam at 130 C., and subjecting the thus obtained yarn, or an article produced therefrom, to a bulking treatment.

This invention relates to a method for producing specific bulky yarns developing no bulkiness in the course of ordinary dyeing operations. More particularly, the invention pertains to a process for preparing said bulky yarns, characterized by using a high shrinking fiber which scarcely shrinks even in the course of dyeing operations carried out by use of hot water at about 100 C. but shrinks at a specific temperature above 100 C., and a low shrinking fiber which scarcely shrinks even at said specific temperature.

As high shrinking components for ordinary bulky yarns, there have been used, acrylic fibers, modacrylic fibers or vinyl chloride fibers and polypropylene fibers which cause high shrinkage by treatment with hot water or steam at above 80 C. Further, as low shrinking components, there have been employed synthetic fibers, natural fibers or regenerated fibers which scarcely cause shrinkage by treatment with hot water or steam at below 110 C. Therefore, the high shrinking components cause shrinkage when subjected, before being made into yarns, to ordinary dyeing operations such as raw stock dyeing or top dyeing and hence cannot be dyed without being provided with bulkiness before they are made into yarns. Further, even after being formed into yarns, they develop bulkiness when subjected to yarn dyeing. However, in the case of knitted and woven fabrics, it is sometimes desirable to develop bulkiness after knitting or weaving, in view of the knitting or weaving conditions or of the quality of the products. This is the case with such knitted products as cardigans, pullovers and underwear, for example. Further, in the case of woven fabrics, it is desirable to apply bulky treatment after yarns have been woven and made into woven fabrics, because yarns which have been subjected to bulky treatment are low in strength and tend to be broken during weaving. In the case of such products, therefore, a synthetic fiber to be used as the high shrinking component is required to be dyed after knitting or weaving unless the fiber is dyed in the form of a tow, or a tow prepared according to dope-dyeing process is used and the dyed tow is hotstretched and is cut to obtain the high shrinking fiber. Therefore, it was impossible to obtain a colored pattern unless the fiber was knit or woven with other fibers, and no sprinkly dyed product could be obtained unless the fiber was subjected to mix-spinning with other fibers. In case a colored tow was to be used, the operations were complex, suffered from much loss and took a long time in making the tow into a finished product, because there were required such steps as dyeing a tow according to a desired dyed pattern, and hot-stretching and cutting the dyed tow. Thus, there were brought about many drawbacks as com pared with the case of raw stock dyeing, top dyeing or yarn dyeing. That is, the process for producing bulky yarns by using a conventional high shrinking component was restricted in commodity, as mentioned above.

In accordance with the method of the present invention, there is used a high shrinking fiber which undergoes no shrinkage even when subjected to ordinary dyeing temperatures of to C., whereby it has been made possible to effect raw stock dyeing, top dyeing and yarn dyeing, and the above-mentioned restriction has been completely removed by effecting bulky treatment after the fiber has been formed into a product.

It is an object of the present invention to provide a method for producing bulky yarns, characterized in making yarns by mix spinning a high shrinking synthetic fiber showing a shrinkage of less than 5% by treatment with hot water at 95-105 C. and a shrinkage of 8-35% by treatment with steam at to 140 C. and as a low shrinking component a fiber showing a shrinkage of less than 10% by treatment with steam at below C., and a yarn comprising said two components is subjected to bulky treatment using hot water or steam at 115 to C. or dry heat of 120 to C.

The present invention will be illustrated in detail below referring to the accompanying drawing. Generally, synthetic fibers undergo shrinkage at elevated temperatures in both dry heat and wet heat, but the shrinkage characteristics thereof vary depending upon the heat career or hot stretching career of the respective fibers. The accompanying drawing shows the curves of shrinkage characteristics of acrylic fiber at elevated temperatures. In the drawing, 1 shows the shrinkage occurring when the fiber, which had been subjected to spinning, stretching and drying under tension, was freely relaxed at elevated temperatures; 2 shows the shrinkage occurring when the fiber, ob-

tained by subjecting the fiber shown by 1 to 3 to relaxing wet heat treatment at 100 C., was subjected to free rel-axing wet heat treatment; 3 shows the shrinkage occurring when the fiber obtained by subjecting the fiber shown by 1 to 3 to relaxing wet heat treatment at 120 C. was subjected to free relaxing wet heat treatment; 4 shows the shrinkage occurring when the fiber, obtained by subjecting the fiber shown by 1 to 3 to relaxing wet heat treatment at 130 C. was subjected to free relaxing wet heat treatment; and 5 shows the shrinkage occurring when the fiber obtained by subjecting the fiber shown by 1 to 3 to relaxing wet heat treatment at 130 C. and had been hot-stretched and fixed under wet heat or dry heat at below 130 C., was further subjected to free relaxing wet heat treatment. Acrylic, modacrylic, vinyl chloride, polypropylene and the like fibers undergo shrinkage at temperatures of about 80 C., regardless of the heat stretching and fixing temperatures. Their curves or absolute shrinkage values vary depending on tensioned and drying temperature in the tension-drying or other production conditions and the polymer composition of respective fibers. In the tension-drying, however, the fiber cannot be treated in an entirely untensioned state and therefore, in the thermal treatment free relaxing curve 1, the shrinkage occurs at a relatively low temperature of 6070 C.

In the case of the general bulky yarns, the high shrinkage components are so prepared as to develop a desired shrinkage by wet heat treatment at about 100 C., i.e., at a dyeing temperature of 100 C. Therefore, as the high shrinking component, there is used, in general, a fiber which, after spinning, stretching and drying, has once been freely relaxed by heat treatment and has been again subjected to hot stretching, i.e., the fiber or curve 5 in the drawing, though there is seldom used a fiber showing the behavior curve 1 in the drawing which has been subjected to spinning, stretching and drying. As the low shrinking component, there is used a fiber freely relaxed at a temperature above 100 C. so that no substantial shrinkage occurs even when subjected to wet heat treatment at about 100 C. That is, there is employed a fiber showing such behavior as the curve 2, 3 or 4 in the drawing. The reason why regenerated fibers and natural fibers are used as the low shrinking components is that they scarcely cause shrinkage by treatment with wet heat at about 100 C.

In the present invention, the high shrinking component to be used is a fiber of curve 2, i.e., a fiber which, after spinning, stretching and tension-drying, has been subjected to free relaxing wet heat treatment at about 100 C.

The fibers serving as the high shrinking components referred to in the present invention are shrinkable fibers showing a shrinkage of less than 5% at 95-105 C. and a shrinkage of =8-35% by treatment with steam at 115- 140 C. Such fibers are prepared from acrylic polymers, modacrylic polymers, vinyl chloride polymers and polyolefinic polymers.

In the above, by acrylic polymers are meant polyacrylo nitrile and copolymers comprising more than 80% by weight of acrylonitrile and less than 20% by weight of a copolymerizable monomer; the modacrylic polymers are polymers comprising 30-80% by weight of acrylonitrile and 70-20% by weight of a vinyl monomer such as vinyl chloride; the vinyl chloride polymers are polymers comprising more than 80% by weight of vinyl chloride and less than 20% by weight of a vinyl monomer such as vinyl acetate and having a polymerization degree of from about 1000 to 3000; and the polyolefinic polymers are copolymers comprising more than 80% by weight of polypropylene and less than 20% by weight of polyethylene.

Methods of producing filamentary materials from said polymers are well known. For example, the dry-spinning of a polypropylene polymer is carried out by dissolving the polymer in kerosene of a fraction having a boiling point between 170 and 250 C., extruding the solution at a rate of 25 m./min. through a spinneret having 30 holes of 100 in diameter, passing the resulting filaments through a vaporization column at a rate of 6 m./min., taking up the filaments onto a bobbin at a rate of 125 m./min., and then stretching the filaments at a ratio of 1:5 to obtain 5 denier filaments having a strength of 7 g./d. and an elongation of 22%. The fiber thus obtained shows a shrinkage of 4% by treatment with steam or in a hot bath at 100 C. and a shrinkage of 14% by treatment with high pressure steam at 130 C.

The fibers serving as the low shrinking components in the present invention may be any of synthetic, natural and regenerated fibers, so far as they show a shrinkage of less than by treatment with steam at below 130 C. and cause no substantial shrinkage at temperatures of 120- 140 C.

The above synthetic fibers include polyamide, polyester, polyurethan, polyethylene, polystyrene, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol and polyacrylic fibers; the natural fibers are cotton, hemp, wool and silk; and the regenerated fibers are viscose, rayon, cuprammonium rayon and nitrocellulose.

Further, even those fibers causing shrinkage at said temperatures may be used, so far as they have previously been subjected to free relaxing wet heat treatment at 120-140 C. to be brought into such a state that they cause no substantial shrinkage at temperatures at which the high shrinking component causes a desired shrinkage.

The proportion of the high shrinking component to be mixed with the low shrinking component is 20-80 weight percent, most preferably 30-50% by weight. That is, the shrinking components to be used in the present invention are fibers of the curves 3 and 4 in the drawing.

For example, as a conventional method, 15 parts of a copolymer (molecular weight 75,000) comprising 90% by weight of acrylonitrile and 10% by weight of methyl acrylate were scoured to a nitrogen oxide content of less than 0.0003%, and were dissolved in 100 parts of 75% nitric acid to obtain a spinning solution. The spinning solution was extruded at 0 C. into a coagulating bath comprising 30% of nitric acid, 6% of calcium nitrate and 64% of water. The resulting filament was advanced at a rate of 6 m./min. by means of a first roller provided at one end of the bath, was water-washed, and was then hot-stretched to 8 times in hot water at C. The thus obtained filaments were freely relaxed with steam at C. to obtain a tow of 3.0 denier acrylic fiber showing a shrinkage of less than 3% by hot water treatment at 100 C. and a shrinkage of 25% by high pressure steam treatment at 130 C. The tow was bias cut to a fiber length of 76-125 mm. and was used as a high shrinking fiber.

On the other hand, nonthermally treated filaments obtained in a manner similar to the above were subjected to free relaxing thermal treatment with high pressure steam at 130 C. to obtain a tow having a monofilamentary denier of 4. The tow was bias cut to a fiber length of 76-125 mm. and was used as a low shrinking fiber.

A copolymer comprising 40% by weight of acrylonitrile and 60% by weight of vinyl chloride was spun to obtain a modacrylic synthetic fiber. The modacrylic fiber was stretched to 5 times at 95 C. and was thermally treated at 95 C. for 10 minutes to obtain a 3 denier fiber showing a thermal shrinkage at 100 C. of 3% and a thermal shrinkage at 130 C. of 22%. The fiber was cut to 102 mm. and the resulting modacrylic synthetic fiber was used as a high shrinking component.

When a yarn comprising such high shrinking fiber and low shrinking fiber is prepared in accordance with the present invention, the high shrinking fiber causes no shrinkage and is not deprived of its high shrinkability in stock dyeing, top dyeing or yarn dyeing, and therefore the yarn can be knitted or woven as a yarn which has not been subjected to bulky treatment (hereinafter referred to as unprocessed yarn). Further, when the yarn is knitted or woven and then subjected to wet heat treatment at -140 C. according to the specificities of the high and low shrinking components, the high shrinking components causes shrinkage to produce bulkiness. Moreover, when the yarn is dyed before knitting or weaving, it is possible to freely attain a desired color, pattern or sprinkly dyed design.

The present invention gives such advantages that not only can unprocessed dyed yarns be produced but there are obtained bulky yarns more rich in bulkiness than the conventional bulky yarns by dyeing the yarns and subjecting the dyed yarns to bulky treatment with high pressure steam. Moreover, the yarns can be dyed in an unprocessed state and therefore the conventional cone dyeing or cheese dyeing is also applicable thereto to make it possible to shorten the steps.

For simplicity of illustration, all the above-mentioned bulky treatment temperatures have been shown by wet heat temperature with steam, but the same is the case with hot water. In the dry heat temperature using hot air, dry heat of 120-180 C. corresponds to wet heat of 115-140 C.

Another great characteristic of the present invention is that, in the case of conventional bulky yarns, the preparation of the high shrinking component requires a hot stretching step, but no such hot stretching step is required in the present invention.

The following examples illustrate the present invention but it should be construed that the present invention is not limited to the examples:

EXAMPLE 1 40% by weight of (A) an acryl fiber of 3 denier and of 76 mm. in fiber length, which had been freely relaxed by treatment with wet heat of 105 C. and showed a shrinkage of 2% according to hot water treatment at 98-100 C. and a shrinkage of 16% according to high pressure steam treatment at C. and 60% of (B) an acrylic fiber of 3 denier and of 76 mm. in fiber length which had been freely relaxed by treatment with wet heat of 130 C. and showed a shrinkage of 5% according to high pressure steam treatment at 130 C. were subjected to mix-spinning to obtain a knitting yarn of a count of 2/ 36 m.

This spun yarn was dyed at 98-100 C. for 1 hour and was then subjected to softening treatment to obtain an unprocessed dyed yarn.

The dyed yarn was then knitted to a full-fashioned cardigan having patterns and was treated in untensioned state with high pressure steam of 130 C. for minutes, whereby a shrinkage of calculated as yarn was caused to obtain a full-fashioned cardigan excellent in bulkiness.

EXAMPLE 2 (C) An acrylic fiber of 3 denier and of 76 mm. in fiber length which had been freely relaxed by treatment with wet heat of 100 C. and showed a shrinkage of 4% according to hot water treatment at 98100 C. and a shrinkage of 12% according to high pressure steam treatment at 125 C. was subjected to stock dyeing at 98- 100 C. for 1 hour, and was then subjected to softening treatment. On the other hand, (D) an acrylic fiber of 3 denier and of 76 mm. in fiber length was dyed at 98- 100 C. for 1 hour and was then subjected to softening treatment. 40% by weight of said fiber (C), of said (D) and 30% by weight of wool, which had been subjected to top dyeing, were mix-spun to obtain a knitting yarn mix-spun with 30% of stock dyed wool which had a count of l/40 m. This yarn was knitted to a jersey of interlocked texture by means of a circular knitting machine having 14 needles per inch, and was then subjected to steam treatment at 125 C. for 5 minutes to obtain a bulky knit jersey.

EXAMPLE 3 by weight of polypropylene fiber (E) (1.5 d., 38 mm.) freely relaxed by wet heat treatment at 95 C. and showing a shrinkage of 2% by hot water treatment at 95- 100 C. and a shrinkage of 12% by high pressure steam treatment at 130 C. was mix-spun with 65% by weight of cotton (commercial Egyptian cotton) scarcely shrinking by high pressure steam treatment at 130 C. to obtain a knitting yarn having a cotton count of 30/ 1. The spun yarn was knitted to a plain stitch by means of a circular knitting machine having 16 needles per inch. The knitted product was dyed in a wince dyeing machine, was subjected to softening treatment and was then treated with steam at 130 C. for 5 minutes in a nontensioned state, whereby a bulky knit material could be obtained.

EXAMPLE 4 A copolymer comprising 40% by weight of acrylonitrile and by weight of vinyl chloride was spun and stretched to obtain a synthetic fiber. The synthetic fiber was subjected to steam treatment at 100 C. in a nontensioned state, whereby a filament showing a shrinkage of 4% by hot water treatment and a shrinkage of 20% by steam treatment at 130 C. was obtained. The filament thus obtained was cut to 3 /2" to prepare a 3 denier staple fiber. 40% by weight of the staple fiber was mixed with 60% by weight of a commercial polyester (3 /2 cut, 3 (1.) showing a shrinkage of 4% by steam treatment at 130 C. The mixed fiber was subjected to worsted-spinning to obtain a two-fold knitting yarn of count of 2/48 m. (first twist 420 m., second twist 250 m.). The knitting yarn was treated with steam at 130 C. for 15 minutes, whereby a bulky knitting yarn could be obtained.

I claim:

1. A method for producing bulky yarns comprising mix spinning a high shrinkage synthetic fiber with a low shrinkage fiber to obtain a yarn, heat shrinking the thus obtained yarn at a temperature of 1l5180 C. to effect a bulking of the yarn, said high shrinkage fiber having a shrinkage of less than 5% by treatment with hot water at 105 C. and a shrinkage of 8+35% by treatment with steam at 115-140" C., said low shrinkage fiber having a shrinkage less than that of the high shrinkage fiber and less than 10% by treatment with steam at below 130 C., said fibers being subjected to a dyeing treatment, prior to the heat shrinking, at a temperature of about C. at which the fibers undergo substantially no shrinkage.

2. A method according to claim 1, wherein said heat shrinking comprises exposing said yarn to hot water or steam at a temperature between C. and C.

3. A method according to claim 1, wherein said heat shrinking comprises exposing said yarnto a dry medium at a temperature between 120 C. and C.

4. A method according to claim 1, wherein the high shrinkage synthetic fiber is acrylic, modacrylic, vinyl chloride, or polypropylene fiber.

5. A method according to claim 1, wherein the low shrinkage fiber is a synthetic, natural or regenerated fiber, having negligible shrinkage in the course of dyeing at 100 C.

6. A method according to claim 1, wherein the proportion of high shrinkage synthetic fiber to low shrinkage fiber is between 20% to 80%.

7. A method according to claim 1 comprising knitting said yarn into an article prior to said heat shrinking.

References Cited UNITED STATES PATENTS 2,575,753 ll/1951 Foster. 3,175,351 3/1965 Bloch. 3,220,085 11/1965 Lund et a1.

LOUIS K. RIMRODT, Primary Examiner. 

